BACKGROUND: Type 2 diabetes (T2D) is a growing epidemic in the U.S. with devastating complications that result in major health and personal costs. To address this, the American Diabetes Association recommends a lifestyle program that focuses on weight loss through caloric restriction and exercise as an initial or an adjunct treatment to pharmacological interventions. However, its general applicability is limited because some individuals with T2D do not need to lose weight, do not want to lose weight, cannot lose weight, or cannot maintain weight loss over a lifetime. Recent research indicates that a major contributor to poor metabolic control is postprandial glucose (PPG) elevation. We have developed a treatment option that focuses on reducing PPG without requiring weight loss. This lifestyle program is comprehensive, integrated, and efficient. Over 5 sessions, this program empowers individuals to use Glycemic load of food, Exercise, and Monitoring glucose (GEM) in a systematic manner. GEM's 1.03% HbA1c reduction compared favorably to both conventional weight loss (0.64% reduction with 42 sessions of Look AHEAD) and continual use of a first line medication (0.9% reduction with Metformin). When enhancing the quantity and quality of glucose feedback with Continuous Glucose Monitoring (CGM), GEM reduced HbA1c by 1.30%. AIMS: This project will determine how GEM compares to conventional weight reduction at short- and long- term follow-up in a large, representative sample of adults with type 2 diabetes. At the same time, we will test a conceptual model based on a review of the literature postulating that the effects of GEM are modulated by the quality and quantity of glucose feedback. This has important implications for long-term maintenance; since the model proposes a cascade in which increasing either the quantity or quality of glucose feedback improves immediate behavior change through positive and negative glucose consequences. These contingencies may lead to improved PPG and insulin sensitivity, and in turn, improved metabolic control. This cascade may produce ancillary benefits that could help maintain long-term success, e.g. greater empowerment and fewer depressive symptoms. APPROACH: 200 participants with poorly controlled T2D will be randomized to 1 of 4 groups that manipulate both the focus on postprandial glucose and the quality and quantity of glucose feedback. Short- and long-term benefits will be assessed using medical, behavioral and psychological measures obtained at baseline, 3 months post-intervention and 12 months post-intervention. IMPACT: If GEM is shown to be effective and enduring, it will provide an alternative to the conventional weight-loss focused lifestyle modification. GEM has the potential to improve metabolic control, increase self- reliance, and slow disease progression. Because GEM is manual-based, it will be easy to deploy and will give it the potential to impact a large proportion of the adults with T2D.